1. Field
Embodiments of the present invention relate to a brake system which may reduce pressure fluctuation which occurs during operation of a piston.
2. Description of the Related Art
A brake system is essentially mounted on a vehicle for braking of the vehicle, and various systems have recently been proposed to obtain stronger and more stable braking force. Examples of the brake system include an anti-lock braking system (ABS), a brake traction control system (BTCS), and a vehicle dynamic control system (VDC). The ABS prevents wheels from skidding upon braking. The BTCS prevents slippage of driving wheels during rapid acceleration from a stop or sudden unintended acceleration of a vehicle. The VDC maintains a stable driving state of a vehicle by controlling a brake oil pressure through a combination of the ABS and the BTCS.
Such a brake system includes a master cylinder to generate a pressure necessary for braking, a plurality of solenoid valves to control a braking oil pressure transmitted to a wheel brake of a vehicle, a low-pressure accumulator to temporarily store oil, a pump and a motor to forcibly pump the oil stored in the low-pressure accumulator, an orifice to reduce the pressure pulsation of the oil pumped by the pump, and an electronic control unit (ECU) to electrically control the operations of the solenoids and the pump. The valve assembly of the solenoids, the accumulator, the pump, and the motor are compactly installed in a hydraulic block (modulator block) made of aluminum, and the ECU is provided with an ECU housing in which the coil assembly of the solenoid valves and a circuit board are embedded, and is coupled to the hydraulic block.
In the conventional brake system as described above, sudden pressure pulsation generated due to driving of the pump in the process of increasing the braking pressure is reduced by the orifice provided at a discharge port of the pump. However, since this is achieved by a structure that adjusts a cross-sectional area of a flow channel simply in order to reduce damping, there may be a limit in completely reducing pressure pulsation.
As another method to reduce pressure pulsation, the number of pistons of a pump may be increased. This method increases the overall performance of a motor and the weight and volume of a module, leading to an increase in manufacturing costs. If a peak of pressure pulsation caused by driving of the pump is successively generated, operating noise in a brake system may occur.